2026 NF Knowledge Series: Discovering Possibilities for Neurofibromatosis Type 1 (NF1) Plexiform Neurofibromas in Adults

The March NF Knowledge Series: Discovering Possibilities for Neurofibromatosis Type 1 (NF1) Plexiform Neurofibromas in Adults webinar was hosted by Mina Lobbous, MD, MSPH. The webinar allowed participants to hear from a leading neuro-oncologist about a potential treatment option and available support resources for adults navigating NF1-related plexiform neurofibromas.

Understanding NF1 and Plexiform Neurofibromas

In a recent session of the Children's Tumor Foundation's (CTF) NF Knowledge Series, the focus was on NF1 and plexiform neurofibromas. The webinar was sponsored by Alexion Pharmaceuticals, a company with over 30 years of experience in treating rare diseases. Joseph Booe, a Patient Education Manager from Alexion, introduced the topic and emphasized the importance of understanding NF1 plexiforms and the potential risks and benefits of treating them with the MEK inhibitor drug, Koselugo® (selumetinib).

Challenges in Treating NF1 Plexiform Neurofibromas

NF1 is a genetic condition that can lead to the development of tumors in various parts of the body. Plexiform neurofibromas, a possible manifestation of NF1, affect 30-50% of people living with NF1. These tumors, although noncancerous, can cause problems depending on their location. For many years, surgery was the only available treatment option, which often couldn't completely remove the tumors due to their complex nature and location. This limitation highlighted the need for alternative treatments, such as Koselugo.

Expanding Access for Adults

Koselugo was the first FDA-approved treatment for NF1, initially approved in 2020 for children with symptomatic, inoperable plexiform neurofibromas. More recently, its approval has expanded to include adults-marking an important step forward and making this treatment option available to a broader group of people living with NF1.

Koselugo: A Targeted Treatment Approach

Dr. Lobbous, an adult neuro-oncology specialist, explained how Koselugo works as a targeted therapy. Unlike traditional chemotherapy, Koselugo inhibits the MEK protein, which is involved in the overactive growth signaling pathway in NF1. This targeted approach helps reduce tumor growth and, in some cases, shrink tumors. The KOMET trial, which led to the FDA approval of Koselugo for adults, demonstrated that 20% of participants experienced significant tumor shrinkage, compared to only 5% in the placebo group.

Outcomes and Implications of Koselugo

The KOMET trial showed that Koselugo is effective in reducing tumor burden in adults with NF1 plexiform neurofibromas. The study included 145 participants and found that 20% of those treated with Koselugo® (selumetinib) achieved a 20% or greater reduction in tumor size. The treatment was generally well-tolerated, with common side effects including rash and diarrhea. Importantly, 87% of participants did not have to permanently stop the treatment due to side effects, indicating a favorable safety profile.

What's Next

The session underscored the importance of a multidisciplinary approach in managing NF1, involving specialists like neuro-oncologists, ophthalmologists, and dermatologists. As research continues, future studies may provide more insights into long-term outcomes and the potential for Koselugo® (selumetinib) to prevent new tumor formation. The ongoing support from organizations like CTF and Alexion plays a crucial role in advancing treatment options and improving the quality of life for those affected by NF1

The development of MEK inhibitors like selumetinib is closely connected to the Children's Tumor Foundation's long-standing role in advancing NF research. By funding early studies and bringing researchers together through collaborative initiatives, CTF helped identify the MEK pathway as a key driver in NF1 tumor growth and supported the science that moved this approach into clinical trials-ultimately contributing to a new treatment option for patients.